By default, Magento compresses the images you upload to increase loading speed and decrease the server load, but presenting your products with high quality images may just provide the extra push to increase conversions in your store. If you find that your product images are too compressed, you can increase image quality by following these simple steps:
1. Locate the file /app/code/core/Mage/Media/Model/File/Image.php
2. Copy file to /app/code/local/Mage/Media/Model/File/Image.php
3. Find this code in the new file (line 174)
$result = imagejpeg($object->getTmpImage(), $object->getFilePath(true), 80);4. Replace with this code
$result = imagejpeg($object->getTmpImage(), $object->getFilePath(true), 95);5. Save the file, upload to your server, and refresh Magento's cache via System > Cache Management.
That's it! If you feel you need more information, check out this thread from the official Magento Forum. Or, for more personalized answers, check out http://magentoexpert.com/ for quick answers from real Magento experts.
